feat(M03): add entity presentation facade

src/render/entities/entity_presentation_snapshot.gd

@@ -0,0 +1,104 @@
+class_name EntityPresentationSnapshot
+extends RefCounted
+
+## Immutable renderer input for one session-local world entity visual.
+## Gameplay authority, identity allocation and asset selection remain external.
+
+const CONTRACT_VERSION := 1
+const SCRIPT_PATH := "res://src/render/entities/entity_presentation_snapshot.gd"
+const ENTITY_ID_SCRIPT := preload("res://src/domain/identity/entity_id.gd")
+const GODOT_WORLD_POSITION_SCRIPT := preload("res://src/domain/coordinates/godot_world_position.gd")
+
+var is_valid: bool:
+	get:
+		return _failure_code.is_empty()
+
+var failure_code: StringName:
+	get:
+		return _failure_code
+
+var entity_id: RefCounted:
+	get:
+		return _entity_id
+
+var world_position: RefCounted:
+	get:
+		return _world_position
+
+var visual_scene_path: String:
+	get:
+		return _visual_scene_path
+
+var yaw_radians: float:
+	get:
+		return _yaw_radians
+
+var uniform_scale: float:
+	get:
+		return _uniform_scale
+
+var is_visible: bool:
+	get:
+		return _is_visible
+
+var _failure_code: StringName
+var _entity_id: RefCounted
+var _world_position: RefCounted
+var _visual_scene_path: String
+var _yaw_radians: float
+var _uniform_scale: float
+var _is_visible: bool
+
+
+## Creates a version-1 full visual snapshot. Invalid values remain inspectable and
+## are rejected without scene mutation by the facade/presenter.
+static func create(
+		entity_id_value: RefCounted,
+		world_position_value: RefCounted,
+		visual_scene_path_value: String,
+		yaw_radians_value: float = 0.0,
+		uniform_scale_value: float = 1.0,
+		is_visible_value: bool = true
+) -> RefCounted:
+	return load(SCRIPT_PATH).new(
+		entity_id_value,
+		world_position_value,
+		visual_scene_path_value,
+		yaw_radians_value,
+		uniform_scale_value,
+		is_visible_value
+	)
+
+
+func _init(
+		entity_id_value: RefCounted,
+		world_position_value: RefCounted,
+		visual_scene_path_value: String,
+		yaw_radians_value: float,
+		uniform_scale_value: float,
+		is_visible_value: bool
+) -> void:
+	_entity_id = entity_id_value
+	_world_position = world_position_value
+	_visual_scene_path = visual_scene_path_value.strip_edges()
+	_yaw_radians = yaw_radians_value
+	_uniform_scale = uniform_scale_value
+	_is_visible = is_visible_value
+	_failure_code = _validate()
+
+
+func _validate() -> StringName:
+	if _entity_id == null or _entity_id.get_script() != ENTITY_ID_SCRIPT or not bool(_entity_id.call("is_valid")):
+		return &"entity_presentation_invalid_entity_id"
+	if _world_position == null or _world_position.get_script() != GODOT_WORLD_POSITION_SCRIPT:
+		return &"entity_presentation_invalid_world_position"
+	for coordinate_name in [&"x_units", &"y_units", &"z_units"]:
+		if not is_finite(float(_world_position.get(coordinate_name))):
+			return &"entity_presentation_position_not_finite"
+	if _visual_scene_path.is_empty():
+		return &"entity_presentation_visual_path_empty"
+	if not is_finite(_yaw_radians):
+		return &"entity_presentation_yaw_not_finite"
+	if not is_finite(_uniform_scale) or _uniform_scale <= 0.0:
+		return &"entity_presentation_scale_invalid"
+	return &""